Breath analyzers such as the portable breath testers used by police for the screening of drivers suspected of driving while under the influence of alcohol require the delivery of a sustained breath sample by the person being tested. Delivery of a proper sample requires the tested person or user to breathe into a sampling head connected to the tester. The sampling head is fitted with a mouthpiece against which the mouth of the user is placed. Such testers are described for example in U.S. Pat. No. 3,764,270 issued to Collier et al. Because the use of conventional breath testers usually occurs under the supervision of a police officer or is voluntary, there is little danger that the sample of gas which is tested will be other than an authentic sample of the breath of the specified person. There are other applications of portable breath analyzers, however, where the authenticity of the breath sample cannot be so easily assured.
For example, sometimes a breath alcohol test is performed by a test subject without human supervision. Where the test subject fears failing the test, he or she may resort to various techniques aimed at circumventing the test including attempts to provide a false sample to the test apparatus. An example of an application in which this is a problem is the breath analyzer incorporated into an ignition interlock system of an automobile or other equipment. Such a system is described in U.S. Pat. No. 4,093,945 issued to Collier et al expressly incorporated herein by reference in its entirety. Vehicle interlock systems, as they are commonly referred to, link an alcohol breath tester to the ignition system of a vehicle such as an automobile. They operate by requiring the user to pass a breath alcohol test before the user's vehicle can be started. Only the delivery of a breath sample with an alcohol content below a predetermined threshold level will enable the ignition system to start the user's engine. Conscientious drivers may install vehicle interlocks in their automobiles as a safety measure and use them voluntarily. On the other hand, the use of an interlock is frequently compelled to some degree. For example, a teen who borrows a family vehicle equipped with an interlock may not be a truly voluntary user. Moreover, the installation of a vehicle interlock is increasingly dictated by court order as a condition for allowing persons convicted of driving under the influence of alcohol to continue to drive.
Another case where breath testing may be performed without direct supervision and where attempts at evasion may be a problem is in a "home arrest" or remote confinement system wherein a prisoner is confined to a designated location and monitored from another location for compliance with behavioral restrictions including abstinence from substances such as alcohol. Such a system is disclosed in co-pending, commonly assigned U.S. patent application Ser. No. 07/041,698 entitled "Remote Confinement System" which is expressly incorporated herein by reference in its entirety.
In the use of a vehicle interlock system, or a remote confinement system which monitors a detainees' abstinence from alcohol, there is usually no supervision by a police officer or other person of the performance of the breath test by the person using the device. Thus, the opportunity exists for the user to attempt to circumvent the test by providing a bogus sample to the tester in lieu of an actual breath sample. Artificial samples may be attempted to be delivered by balloons or hoses attached to the mouth of the tester. If successful, the test apparatus may erroneously analyze this gas as it would an authentic breath sample and enable the starting of the engine. Subjects may also attempt to circumvent the interlock by passing the breath sampling mouthpiece to an accomplice who has not been drinking in excess. The accomplice cooperates with the intended subject by providing a substitute breath sample.
A vehicle interlock system which is specially adapted to permit unsupervised confirmation of the identity of a designated user is described in detail in co-pending U.S. patent application Ser. No. 907,881 which is expressly incorporated herein by reference in its entirety. In that system, the designated test subject is trained to perform an identity-confirming act which is not readily learnable in fewer than a certain number of attempts. Successful performance of this act within a predetermined number of attempts confirms the identity of the subject and permits the breath test to be passed if the breath is below a specified alcohol limit. The system requires that at least a portion of the identity-confirming act, which preferably consists of a coded sequence of timed breath pulses and pauses, to take place substantially contemporaneously with at least a portion of the delivery of the breath sample to be measured. This helps to avoid circumvention by having the designated subject perform the identity-confirming act but having an accomplice who has not been drinking in excess deliver a substitute breath sample.
One may also attempt to defeat alcohol breath tests, particularly those required by vehicle interlock systems, through the use of filters, such as charcoal filters, which tend to remove alcohol from the breath sample being delivered. Such attempts are made by placing a filter over the mouthpiece of the breath tester and then blowing through the filter into the mouthpiece. Some filters can remove enough alcohol from the breath sample entering the sampling tube to permit the breath test to be evaded by a prospective driver whose unfiltered breath exceeds the permissible alcohol limit.
Accordingly, there is a need for an improved mouthpiece for use with alcohol breath testers, particularly those used without supervision, to reduce the likelihood of the success of the abuses discussed above. As such, it is an objective of the present invention to provide a mouthpiece for a breath tester which will effectively deter efforts directed to circumventing the delivery of a valid breath sample, even when the test is performed without supervision.
It is a further objective of the present invention to provide a mouthpiece to which methods of delivering an artificial sample are difficult to adapt.
It is a further objective of the present invention to provide a mouthpiece for a breath analyzer which may be adapted to help detect, and therefor deter, attempts to transfer the mouthpiece between the desired test subject and an accomplice or a bogus delivery device such as a balloon or gas bottle.
It is yet a further objective of the present invention to provide a mouthpiece for a breath analyzer which effectively deters the use of filtering devices to reduce the alcohol content of the breath.
It is a still further objective of the present invention to provide a mouthpiece adapted to cue the test subject to begin or cease some phase of the test sequence such as the performance of the identity-confirming act or delivery of a breath sample.
It is a further objective of the present invention to provide such a mouthpiece wherein cuing is accomplished by direct electrical stimulation to further frustrate attempts to deliver a bogus sample by filter means or the like and to make teaching of the identity-confirming act to an accomplice more difficult.